There exists an inbred line of chickens at the University of California, Davis, which develops idiopathic scoliosis. Our initial investigations indicate that there is no abnormality in the differentiation of the spine nor in its growth centers, and as in humans, the bony changes of the spine appear to be secondary to the curve. Similarly, a study of the paravertebral muscles and neurological elements and biochemical analysis of the connective tissue has not led to the discovery of an obvious defect causing this scoliosis, although abnormalities requiring further investigations do exist. Our objectives for this proposed research project are to examine more closely the neurologic elements in these animals with particular reference to the proprioceptive and sensory aspects of the spinal cord and adjacent structures, to further study the paraspinous muscles by examining their physiological activity with electromyography, and to examine their embryologic development to see if some transitory changes might be responsible for the scoliosis. We also plan to study the biomechanical strength of the connective tissue and ligaments about the spine to see if there are any differences in the strength of these support structures. In the early embryos we plan to manipulate their growth using a biolaser to see if we can influence the development of scoliosis by selective destruction of different elements. A similar technique will be used to attempt to produce scoliosis in normal chickens. Finally, we plan to select for an increased incidence of scoliosis in our current line and to develop new sublines by a program of crossing to an isogenic SCW Leghorn stock available here. We will continue efforts to improve fertility and hatchability in these stocks so that experimental material will be available for other investigators.